Affinage

RC3H2

Roquin-2 · UniProt Q9HBD1

Length
1191 aa
Mass
131.7 kDa
Annotated
2026-04-28
25 papers in source corpus 7 papers cited in narrative 7 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

RC3H2 (Roquin-2) is a cytoplasmic RNA-binding E3 ubiquitin ligase that couples post-transcriptional mRNA regulation with ubiquitin-dependent protein degradation to control immune homeostasis and oxidative stress responses. Its bipartite ROQ+HEPN domain undergoes large conformational changes to bind stem-loop and duplex RNA structures, targeting mRNAs such as ICOS and TNF for decay via stress granule-associated pathways, functioning redundantly with its paralog Roquin-1 to suppress T follicular helper cell accumulation (PMID:20412057, PMID:23583642, PMID:26489670). The RING finger domain catalyzes K48-linked polyubiquitination of the MAP3 kinases ASK1 and TAK1 under oxidative stress, promoting their proteasomal degradation and thereby attenuating JNK/p38 MAPK and Nrf2 survival signaling to switch cell fate toward apoptosis (PMID:24448648, PMID:38729452). RNA duplex binding cross-talks with E3 ligase activity, and RC3H2 engages a specific set of E2 ubiquitin-conjugating enzymes partially overlapping with those used by RC3H1 (PMID:26489670).

Mechanistic history

Synthesis pass · year-by-year structured walk · 6 steps
  1. 2000 Medium

    Initial cloning established that RC3H2 encodes a protein with dual nucleic-acid-binding (CCCH zinc finger) and E3 ligase (RING finger) domains, raising the question of how these activities are coordinated.

    Evidence cDNA cloning with site-directed mutagenesis of zinc finger reducing DNA binding, subcellular fractionation and immunofluorescence in mammalian cells

    PMID:10938276

    Open questions at the time
    • Single study without independent replication of perinuclear localization
    • RNA versus DNA substrate preference not resolved
    • No functional consequence of RING domain established
  2. 2010 High

    Identification of the ROQ domain as the module responsible for RNA binding and stress granule localization resolved how RC3H2 engages target mRNAs and established Icos mRNA decay as a direct functional readout.

    Evidence SPR, gel-shift, and footprinting for RNA binding; fluorescence microscopy with domain truncations for stress granule localization

    PMID:20412057

    Open questions at the time
    • Structural basis of ROQ-RNA recognition not yet determined
    • Whether stress granule localization is required for mRNA decay not tested
    • E3 ligase activity not linked to mRNA regulatory function
  3. 2013 High

    Genetic studies revealed that RC3H2 and RC3H1 function redundantly to repress ICOS and TNF mRNAs and suppress T follicular helper cell accumulation, establishing the physiological importance of Roquin-2 in immune homeostasis.

    Evidence Mouse genetics with RING and ROQ domain point mutants, flow cytometry, in vivo arthritis model

    PMID:23583642

    Open questions at the time
    • Unique non-redundant functions of RC3H2 versus RC3H1 not delineated
    • Full mRNA target repertoire of RC3H2 not defined
    • Whether RING E3 ligase activity contributes to mRNA target regulation in vivo unknown
  4. 2014 High

    Demonstration that RC3H2 ubiquitinates ASK1 for proteasomal degradation under oxidative stress revealed a second major function—direct regulation of MAPK signaling kinases—beyond mRNA decay, with cross-species conservation in C. elegans.

    Evidence siRNA screen in HeLa cells, co-immunoprecipitation, in vitro ubiquitination assay, H₂O₂ treatment, C. elegans genetics

    PMID:24448648

    Open questions at the time
    • Ubiquitin chain linkage type on ASK1 not specified
    • Whether RNA-binding and E3 ligase functions are coordinated in the same cellular context unclear
    • Structural basis of ASK1 recognition not determined
  5. 2015 High

    Crystal structures of the ROQ+HEPN domain in apo and RNA-bound states provided the atomic-level mechanism for RNA duplex recognition and revealed functional crosstalk between RNA binding and E3 ubiquitin ligase activity.

    Evidence X-ray crystallography, SAXS, E2 enzyme profiling, in vitro auto-ubiquitination assay

    PMID:26489670

    Open questions at the time
    • Structural basis of RING-E2 interaction not resolved
    • How RNA binding modulates ubiquitination in a cellular context not shown
    • No co-structure with a ubiquitination substrate
  6. 2024 High

    Identification of TAK1 as a second kinase substrate ubiquitinated with K48-linked chains via oxidative-stress-induced disulfide bonding established a redox-sensing mechanism by which RC3H2 switches cell fate from Nrf2-mediated survival to death.

    Evidence Co-immunoprecipitation, K48-linkage-specific ubiquitination assay, cysteine mutagenesis, knockout MEF rescue, TAK1 pharmacological inhibition

    PMID:38729452

    Open questions at the time
    • Whether disulfide-mediated oligomerization is a general mechanism for all RC3H2 substrates unknown
    • In vivo physiological relevance in immune cells not tested
    • Quantitative threshold of ROS required to activate this switch not defined

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the RNA-binding and E3 ubiquitin ligase functions of RC3H2 are integrated in the same signaling context—and whether RNA binding regulates substrate ubiquitination in vivo—remains an open mechanistic question.
  • No in vivo demonstration that RNA binding and ubiquitination are coupled on the same target complex
  • Full substrate and mRNA target repertoire not systematically mapped
  • Unique non-redundant functions versus RC3H1 remain poorly defined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003723 RNA binding 4 GO:0140096 catalytic activity, acting on a protein 4 GO:0016874 ligase activity 3
Localization
GO:0005829 cytosol 2
Pathway
R-HSA-392499 Metabolism of proteins 3 R-HSA-162582 Signal Transduction 2 R-HSA-168256 Immune System 2 R-HSA-8953854 Metabolism of RNA 2 R-HSA-8953897 Cellular responses to stimuli 2
Partners
ASK1ICOSRC3H1TAK1

Evidence

Reading pass · 7 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 RC3H2 (MNAB) encodes a membrane-associated nucleic acid-binding protein with a C3HC4 RING finger and a CCCH zinc finger; mutagenesis of a conserved amino acid in the zinc finger reduced DNA binding by 50%, and the protein localizes primarily to the perinuclear space (endoplasmic reticulum or trans-Golgi network). cDNA cloning, site-directed mutagenesis, immunoprecipitation, subcellular fractionation/immunofluorescence The Journal of biological chemistry Medium 10938276
2010 The ROQ domain of Roquin-2 (RC3H2/MNAB) is necessary and sufficient for localization to arsenite-induced stress granules and can induce stress granule formation upon overexpression; the ROQ domain also directly binds RNA from the Icos 3'-UTR and is required to trigger Icos mRNA decay. Fluorescence microscopy, gel-shift assay, surface plasmon resonance (SPR), footprinting, domain truncation/deletion The FEBS journal High 20412057
2013 Roquin-2 (RC3H2) shares redundant functions with Roquin-1 in repressing ICOS mRNA and suppressing T follicular helper cell accumulation; the RING domain of Roquin-1 (not Roquin-2) is required for stress granule localization, and loss of the Roquin-1 RING domain allows Roquin-2 to compensate in ICOS and Tfh cell repression. Both paralogs also target TNF mRNA in non-lymphoid cells. Mouse genetics (RING and ROQ domain point mutants), fluorescence microscopy (stress granule localization), flow cytometry, in vivo arthritis model Immunity High 23583642
2014 Roquin-2 (RC3H2) functions as an E3 ubiquitin ligase that ubiquitinates ASK1 (MAP3K5) upon ROS stimulation, promoting its proteasomal degradation; knockdown of Roquin-2 leads to sustained ASK1, JNK, and p38 MAPK activation and increased cell death. This mechanism is evolutionarily conserved, as the C. elegans ortholog RLE-1 similarly regulates the ASK1 ortholog NSY-1 during bacterial infection. siRNA screen in HeLa cells, co-immunoprecipitation, ubiquitination assay, H2O2-induced ROS treatment, C. elegans genetics Science signaling High 24448648
2015 Crystal structures of the RNA-binding region of RC3H2 in apo and RNA-bound forms reveal a bipartite ROQ+HEPN domain architecture; both domains undergo large conformational change to accommodate RNA duplex binding. RC3H2 interacts with a set of E2 ubiquitin-conjugating enzymes (overlapping but not identical to RC3H1) to drive polyubiquitin chain assembly, and RNA duplex binding cross-talks with its E3 ubiquitin ligase activity as shown by in vitro auto-ubiquitination assay. X-ray crystallography (apo and RNA-bound structures), SAXS, in vitro RNA-binding assays, E2 enzyme profiling, in vitro auto-ubiquitination assay Scientific reports High 26489670
2024 Roquin-2 (RC3H2) promotes K48-linked polyubiquitination and proteasomal degradation of TAK1 under excessive oxidative stress conditions; it interacts with TAK1 via four cysteine residues (C96, C302, C486, C500) that form oxidative stress-induced disulfide-bond oligomers. This suppresses TAK1-mediated Nrf2 activation and switches cell fate from survival to death. Roquin-2-deficient MEF cells showed sustained Nrf2 activation and resistance to lethal ROS, reversed by TAK1 inhibition. Co-immunoprecipitation, ubiquitination assay (K48-linkage specific), cysteine mutagenesis of TAK1, knockout MEF cells, pharmacological/genetic TAK1 inhibition, western blot Free radical biology & medicine High 38729452
2025 RC3H2 (Roquin-2), an RNA-binding E3 ubiquitin ligase, can be recruited by engineered circular RNAs (circRNAs) containing binding sites for both RC3H2 and target RNA-binding proteins (FUS or hnRNPA1), forming ternary complexes that promote degradation of the target RBPs; ALS-mutant FUS-P525L and hnRNPA1-P288S protein levels were reduced ~20–30% by this approach. RNA immunoprecipitation, protein analysis (western blot), engineered circular RNA expression, ternary complex detection Molecular therapy. Methods & clinical development Medium 40687373

Source papers

Stage 0 corpus · 25 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2013 Roquin-2 shares functions with its paralog Roquin-1 in the repression of mRNAs controlling T follicular helper cells and systemic inflammation. Immunity 122 23583642
2010 The ROQUIN family of proteins localizes to stress granules via the ROQ domain and binds target mRNAs. The FEBS journal 71 20412057
2020 Long Noncoding RNA RC3H2 Facilitates Cell Proliferation and Invasion by Targeting MicroRNA-101-3p/EZH2 Axis in OSCC. Molecular therapy. Nucleic acids 66 32163895
2002 Human osteoblasts' proliferative responses to strain and 17beta-estradiol are mediated by the estrogen receptor and the receptor for insulin-like growth factor I. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 64 11924572
2014 Roquin-2 promotes ubiquitin-mediated degradation of ASK1 to regulate stress responses. Science signaling 59 24448648
2023 The impact of rare protein coding genetic variation on adult cognitive function. Nature genetics 43 37231097
2020 The effect of aging on the biological and immunological characteristics of periodontal ligament stem cells. Stem cell research & therapy 42 32727592
2000 A human gene coding for a membrane-associated nucleic acid-binding protein. The Journal of biological chemistry 37 10938276
2020 Reducing False Negatives in COVID-19 Testing by Using Microneedle-Based Oropharyngeal Swabs. Matter 36 33043290
2015 New Insights into the RNA-Binding and E3 Ubiquitin Ligase Activities of Roquins. Scientific reports 29 26489670
1996 Inhibition of apoptotic cell death in B-CLL by interferon gamma correlates with clinical stage. Leukemia 29 8892682
1999 A peptide derived from a polyreactive monoclonal anti-DNA natural antibody can modulate lupus development in (NZBxNZW)F1 mice. Immunology 26 10233713
2020 Genetic loci associated with prevalent and incident myocardial infarction and coronary heart disease in the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. PloS one 7 33186364
2012 Alopecia in a viable phospholipase C delta 1 and phospholipase C delta 3 double mutant. PloS one 6 22723964
2024 Roquin-2 promotes oxidative stress-induced cell death by ubiquitination-dependent degradation of TAK1. Free radical biology & medicine 4 38729452
2013 Magnetism and magnetic structures of PrMn2Ge2-xSix. Journal of physics. Condensed matter : an Institute of Physics journal 4 23988490
2023 Uncommon Protein-Coding Variants Associated With Suicide Attempt in a Diverse Sample of U.S. Army Soldiers. Biological psychiatry 3 38141912
1995 Efficacy of subcutaneous application of live infectious bursal disease vaccine in young chickens with maternally derived antibody. The Journal of veterinary medical science 3 8519892
2025 Using circular RNAs to target toxic RNA-binding proteins in amyotrophic lateral sclerosis. Molecular therapy. Methods & clinical development 2 40687373
2023 Construction of ceRNA regulatory networks for osteoporosis. Molecular medicine reports 2 37326104
2021 Selection, identification, and characterization of SARS-CoV-2 monoclonal antibody resistant mutants. Journal of virological methods 2 33513380
2019 Correlation between the results of two analytical methods for measuring measles virus neutralizing antibodies in source plasma and therapeutic immunoglobulin products. Biologicals : journal of the International Association of Biological Standardization 2 30992162
2025 Genetic polymorphisms as predictors of the response of hepatocellular carcinoma patients to doxorubicin chemotherapy: a genome-wide association study. Frontiers in pharmacology 1 40535770
2025 Rational Design of Copper-Based Metallic Nano-Antibiotic against Drug-Resistant Bacteria Infection. Small (Weinheim an der Bergstrasse, Germany) 0 40739837
2001 [Production and characterization of monoclonal antibodies directed agains the major outer membrane protein and lipopolysaccharide of Chlamydia trachomatis]. Revista Argentina de microbiologia 0 11833251